1. Field of the Invention
The present invention generally relates to amplifier circuits providing wideband amplification with minimal noise, and in particular, to amplifier circuits utilizing pairs of functionally complementing devices.
2. Description of the Related Art
A gain-bandwidth product as well as a noise factor of a field effect transistor (hereinafter xe2x80x9cFETxe2x80x9d) limits the FET""s ability to amplify low-level voltage input signals over a wide range of frequencies. Additionally, a gain-bandwidth product as well as a noise factor of a magnetic tunnel junction device (hereinafter xe2x80x9cMTJxe2x80x9d) limits the MTJ""s ability to amplify low-level current input signals over a wide range of frequencies.
In radio frequency and microwave circuits, the gain of amplifiers utilizing a FET or MTJ as an active filter can be increased by narrowing the pass band of the FET or MTJ. However, that gain responses are not flat and often have phase discontinuities. Furthermore, the noise performance is poorer when stages are cascaded.
The high frequency electronic industry is therefore continually striving to improve the gain-bandwidth product of amplifying circuits.
The present invention relates to an amplifier circuit which utilizes duality of devices to provide high gain-bandwidth product.
A FET and MTJ are connected in functional cascade to best utilize the amplification, impedance, noise, and operating mode characteristics of each device. This composite utilizes a synergistic improvement in the gain bandwidth of such cascaded pair. In one form the MTJ input is the load of the FET. In another form, the FET input (gate electrode) is the load of the MTJ. The FET/MTJ composite matches respective desirable impedance characteristics while eliminating the noise introduced by resistors in conventional cascade configurations.
The foregoing forms and other forms, features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof.